01 Email

I think this is the fundamental basic requirement from which many other digital assets may spring or are supported. This would be an email address that the person identifies with and has some personal investment in. i.e. it is not simply a string of numbers or include a bunch of numbers to make their name unique. The person chose this email address, it was not handed out to them by some agency. They can easily dictate their address to you just like hey can their postal address and they do not rely on a scrap of paper. Ideally the person can access their email from a variety of locations and it is not dependent on being logged on at home via a password their computer remembers but which they have long since forgotten. An understanding of phishing and hoaxes and ability to deal spam without being freaked out is good. The person adopts a degree of "netiquette" and responds to messages in reasonable time. This is a useful reference: http://emailcharter.org/